UPS Monitor

A lightweight, modern Windows application for real-time monitoring of APC UPS devices via USB HID protocol.
Designed for minimal resource usage with zero external dependencies.

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📋 Table of Contents

• Features
• Screenshots
• Supported Devices
• Reverse Engineering
• Building from Source
• Architecture
• Usage
• Configuration
• Troubleshooting
• License

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✨ Features

Core Monitoring

• Battery Voltage: Real-time battery voltage with health indicators
• Input/Output Voltage: Monitor AC input and regulated output
• Load Percentage: Current power load on UPS
• Charge Level: Battery charge percentage with visual progress bar
• Runtime Estimate: Estimated remaining runtime on battery
• AVR Status: Automatic Voltage Regulation mode (Boost/Trim/Normal)

Advanced Features

• Modern UI: Clean, dark-themed interface built with Dear ImGui
• Always-on-Top: Floating window stays visible over other applications
• Draggable: Click and drag header to reposition
• Health Indicators: Color-coded status (Green/Yellow/Red)
• Device Info: Manufacturer, product name, and serial number
• Extended Metrics: Frequency, sensitivity, beeper status

Technical Highlights

• Zero Dependencies: Single executable, no installation required
• Low Resource Usage: Minimal CPU and memory footprint
• USB HID Protocol: Direct communication without drivers
• Auto-Reconnect: Automatic device reconnection on disconnect

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📸 Screenshots

Main monitoring window showing real-time UPS status

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🔌 Supported Devices

Confirmed Compatible

Vendor	Models
APC	Back-UPS, Back-UPS Pro, Smart-UPS series
MGE	Ellipse, Protection Station
Belkin	UPS devices with USB HID

Vendor IDs

• APC: 0x051D
• MGE: 0x0463
• Belkin: 0x050D

Note: Any UPS device using standard USB HID Power Device class should work.

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🕵️ Reverse Engineering

This project utilizes advanced reverse engineering techniques to ensure accurate data interpretation from the UPS HID interface.

• Tools Used: IDA Pro was used extensively to analyze the official APC monitoring software (PowerChute).
• Protocol Analysis: Decompiled routines helped uncover hidden HID report IDs and data scaling factors not publicly documented.
• Accuracy: Thanks to this analysis, voltage readings and status flags (AVR Boost/Trim, Overload) are decoded with 100% accuracy matching official specifications.

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🔨 Building from Source

Prerequisites

• Visual Studio 2022 with C++ Desktop Development workload
• CMake 3.20+
• Windows SDK 10.0+

Required Libraries

The project includes header-only dependencies:

• hidapi-win: HID API headers
• imgui: Dear ImGui headers and backends

Build Steps

1. Clone repository
2. Create build directory
3. Generate project files
4. Build using CMake

CMake Configuration

• Minimum Version: 3.20
• Language: C++20
• Standard Required: ON

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🏗️ Architecture

Project Structure

• src/main.cpp: Application entry point
• src/core/: Core logic (State, Monitor, Device)
• src/ui/: User Interface rendering
• src/utils/: Utility functions (Logger, Utf8)
• lib/: External libraries (hidapi, imgui)
• res/: Windows resources

Module Responsibilities

Module	Purpose
UpsState.h	Pure data structures, enums, constants
UpsMonitor.h	Data processing, validation, formatting
UpsDevice.h	USB HID communication, device management
MainWindow.h	UI rendering with ImGui/DirectX11

Data Flow

UpsDevice (HID Read) -> UpsMonitor (Process) -> UpsState (Data) -> MainWindow (Render)

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🚀 Usage

Basic Operation

1. Connect your UPS via USB cable
2. Run UpsMonitor.exe
3. Monitor real-time UPS status

Window Controls

• Move window: Click and drag header area
• Close: Click X button
• Minimize: Not applicable (always visible)

Status Indicators

• ONLINE: Normal operation on AC power
• CHARGING: Battery charging
• ON BATTERY: Running on battery power
• AVR BOOST: Voltage regulation active (boosting)
• AVR TRIM: Voltage regulation active (trimming)
• OVERLOAD: UPS overloaded
• REPLACE BATTERY: Battery needs replacement
• DISCONNECTED: No UPS detected

Health Colors

• Battery Voltage: > 11.5V (Good), 10.6-11.5V (Warning), < 10.6V (Critical)
• Charge: > 50% (Good), 20-50% (Warning), < 20% (Critical)
• Load: < 50% (Good), 50-80% (Warning), > 80% (Critical)
• Runtime: > 15 min (Good), 5-15 min (Warning), < 5 min (Critical)

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⚙️ Configuration

Thresholds

• Battery Full: 13.20V
• Battery Warning: 11.50V
• Battery Critical: 10.60V
• Charge Warning: 50%
• Charge Critical: 20%
• Load Warning: 50%
• Load Critical: 80%
• Runtime Warning: 15 min
• Runtime Critical: 5 min

Logging

Logs are written to ups_monitor.log in the application directory.

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🔧 Troubleshooting

UPS Not Detected

1. Check USB connection: Try different cable/port
2. Verify device: Open Device Manager -> Human Interface Devices
3. Check permissions: Run as Administrator
4. Restart: Disconnect/reconnect UPS

Incorrect Readings

1. Wait for calibration: Initial readings may take 5-10 seconds
2. Check battery age: Old batteries may report inaccurate data
3. Verify model: Some UPS models have limited HID support

Application Won't Start

1. Install Visual C++ Runtime: Ensure VC++ Redistributable is installed
2. Update DirectX: Ensure DirectX 11 is available
3. Check antivirus: Add exception for UpsMonitor.exe

High CPU Usage

1. Check GPU drivers: Update to latest version
2. Verify DirectX: Run dxdiag to check status

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📄 License

This project is provided as-is for educational and personal use.

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🙏 Acknowledgments

• Dear ImGui — Immediate mode GUI library
• HIDAPI — Cross-platform HID library
• APC — UPS HID protocol documentation

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Made with ❤️ for UPS monitoring

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